Downloaded from https://www.everyspec.com MIL-STD-1311D SURVIVAL-RATE LIFE 1. Purpose. This test is designated to maintain quality level in terms of early life survival. 2. Procedures. a. Select samples in accordance with MIL-PRF-1, section 4. b. Test tubes at 100 hours as specified in method 1201. When any tap-short indication is obtained, the test shall be repeated. When any tap shorts are again obtained, the tube shall be rejected as inoperable. c. Determine the number of tubes defective at the 100-hour period. d. If more than the allowable number of defectives occur, declare the lot nonconforming. e.
A resubmitted lot shall be subjected to all conformance inspection, part 1 and part 2 tests, except the following: Vibration tests Shock tests Physical (including dimensions) Secureness of base, cap, or insert Lead fatigue Barometric pressure, reduced Base strain (miniature) Glass strain 3. Equivalent conditions. For survival-rate life test, the equivalent stability-life-test conditions shall be interpreted as having the same heater voltage (Ef) and heater-cathode voltage (Ehk) as the stability life test; and the same interruption rate as the intermittent life test.
The electrode voltages shall be such that the element dissipations are not less than 80 percent nor more than 100 percent of stability-life-test anode dissipation. These voltages shall be maintained within the limits of 50 percent minimum and 200 percent maximum of specified voltage. METHOD 1521 METHOD 1521 1521-1 19 April 1968